This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.
In general, manholes or examination holes are formed at predetermined locations to work such as repair or replacement of pipes or electric wires for waterworks, sewerages, communication, and city gas under the ground, and cover bases and manhole covers are installed and fixed at the entrance of the manholes and examination holes for workers to be able to get under the ground to examine those facilities.
However, those manhole covers cannot be adjusted in height and inclination, so it is required to specifically adjust the heights in order to level the tops of the cover bases and the surfaces of roads, and accordingly, a large amount of manhole covers on roads are a main factor that make the roads bumpy.
In detail, industrial manholes are circular or rectangular concrete structure and are composed of a manhole body connected with channels and an examination hole formed through the top of the manhole body for people or machines can pass it to work, and a manhole cover is installed over the examination hole.
That is, a manhole cover is supposed to be disposed over a manhole and fixed to be leveled with the surface of a road, but it is difficult to adjust the manhole cover, so a base for adjusting height is separately installed under the manhole cover to adjust height.
According to the existing manholes, however, the surfaces of roadways are damaged by vehicles for the specific characteristics of the roadways, so they are necessarily repaired, for example, by pavement, but when the surface of a road becomes higher or lower due to repair work, it is impossible to effectively adjust the height of a manhole cover.
Further, it is impossible to finely adjust the inclination and height of a manhole.
Accordingly, there is a need for developing a manhole cover of which the height and inclination can be variously adjusted to solve these problems.